Multraship has taken delivery of the first of two Carrousel Rave Tugs (CRTs) which will make it easier, safer and more environmentally friendly to work with seagoing vessels at much higher speeds than conventional tugs can safely achieve, and without the risk of capsizing under a tow-load.
The vessel, commissioned as Multratug 32, was delivered by Damen Maaskant in Stellendam, the Netherlands, and will operate under lease to Multraship. Multratug 32 is 32 m long, has a maximum static bollard pull of 77 tonnes, and is powered by two Voith thruster units and two ABC main engines delivering 2650 kW at 1000 rpm. Top speed is over 14 knots.
The contract for the vessels was agreed between Novatug, an innovation arm of the group to which Multraship also belongs, and Damen’s specialist propulsion subsidiary Van der Velden Barkemeyer GmbH in November 2015. German shipyard Theodor Buschmann GmbH in Hamburg assembled the hulls, which were then moved to Stellendam for fitting-out.
Rave Concept and Carrousel System
The Multratug 32 combines for the first time two innovative technologies – the Rave concept employing the longitudinal alignment of two VSP drives (in contrast to the more conventional transverse ‘tractor’ configuration) and the Carrousel Towing system. The Rave concept was initially devised by naval architects Robert Allan and Voith in Germany and thereafter developed further and optimised by the introduction of the Carrousel. Machinefabriek Luyt in Den Oever delivered the specially developed winch, while ABC in Belgium was responsible for the engines.
Julian Oggel, managing director of Novatug, says, ‘The whole CRT concept was driven by safety considerations. In principle, capsizing is impossible when towing with the Carrousel, which facilitates the safe execution of manoeuvres that would be very high-risk with traditional tugs.’
The Carrousel Towing system does away with fixed towing points and instead mounts the winch on a freely rotating steel ring seated around the base of the tug’s superstructure. This not only allows the tug to turn completely freely while maintaining tension on the towing line, but also permits the tug to use the lateral resistance of the hull as a powerful braking mechanism. As a result, a Carrousel Tug can brake and steer a moving tow faster and more effectively than a conventional vessel and is impossible to capsize.
Use of Kinetic Energy
Pepijn Nuijten, managing director of Multraship Towage & Salvage, says, ‘Thanks to the ingenious design of the tug, which effectively maximises the use of the kinetic energy available in the towed vessel rather than the tug’s own engine power only, the same towing force can be achieved at much lower levels of fuel consumption than with a conventional tug.’
Energy Savings and Emission Reduction
‘The savings amount to at least 25% on an average operation involving a seagoing vessel. We have been using sustainable Eco2Fuel+ diesel from De Pooter Oil since trials began, resulting in emissions of soot and particulate matter being reduced by a further 16.5%, and a reduction in carbon emissions of 44.7%.’
Damen is currently building a second, identical CRT for Novatug. Delivery is expected in May 2018 and the vessel has already been reserved for Multraship. Novatug also plans to market smaller versions of the CRT.
